<template>
<div>
  <el-input v-model="value1" placeholder="费用1"></el-input>
  <el-input v-model="value2" placeholder="费用2"></el-input>
  <p>合计: "{{ sum }}"</p>
</div>
</template>

<script>
export default {
    data() {
        return {
            value1:0,
            value2:0,
        }
    },
    computed:{
        sum: function(){
            return this.value1 + this.value2;
        }
    }
}
</script>